Conventionally, in a transmission apparatus, a service operation is performed in a state in which both an active interface (IF) board (ACT system) and a standby IF board (SBY system) are mounted on the transmission apparatus in anticipation of a failure, such as line abnormality or a hardware failure. With such a transmission apparatus, a process is performed by the active IF board after the start until a failure occurs in the active IF board. Furthermore, the standby IF board is kept in a standby state until a failure occurs. If a failure occurs in the active IF board, the process is switched to the standby IF board and the process that was being performed by the active IF board is taken over by the standby IF board. A processes performed by the active IF board and the standby IF board can be, for example, a conversion process that converts an electrical signal to/from an optical signal or a process for performing predetermined processing, such as amplification, on a signal that has been transmitted/received.
However, electrical power is supplied to the standby IF board even though it is in a standby state and thus the standby IF board consumes electrical power. The reason for this is to avoid an instantaneous power interruption when the process is switched from the active IF board to the standby IF board and to provide a seamless service for a user.
In contrast, in recent years, the reliability of IF boards has increased due to improvements in the durability of components used in the transmission apparatus. Accordingly, even if the operation of the standby IF board is stopped and no electrical power supplied to it until there is a high possibility that a failure occurs due to, for example, degradation of the active IF board, an instantaneous power interruption is less likely to occur.
The use of a conventional technology has been proposed to reduce electrical power consumption by stopping a process performed by a standby optical interface board. Furthermore, the use of a conventional technology has also been proposed to reduce electrical power consumption by setting the power supply of a standby transmitting unit that is not performing communication to an off state.    Patent Document 1: Japanese Laid-open Patent Publication No. 7-95132    Patent Document 2: Japanese Laid-open Patent Publication No. 2005-27173
There is a problem however in that even if the reliability of the IF board is improved, the active IF board may possibly become degraded due to insertion and extraction of the IF board to/from the transmission apparatus or due to conditions changing over time. In a state in which a failure rate increases due to the degradation of the active IF board, there is a high possibility that a process will be switched to the standby IF board. Accordingly, if the active IF board is degraded, it is preferable to make a state in which switching to the standby system can be immediately performed in order to cope with an instantaneous power interruption.
With the conventional technology for stopping a process performed by a standby IF board, because electrical power is supplied to the standby IF board, the electrical power consumption is not sufficiently reduced. Furthermore, with the conventional technology for reducing the electrical power consumption by turning off the power supply, even if the probability of switching boards increases due to the degradation of the active IF board, because power is not supplied to the standby IF board, an instantaneous power interruption may possibly occur at the time of switching boards.